THE RUBY IN JEWELRY

RUBY CHARACTERISTICS
 

The ruby—like the sapphire—belongs to the corundum family. Simply put, a ruby ​​is a variety of red sapphire so rare and highly prized that it has been given its own name: ruby.
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The ruby ​​is a gemstone defined by three key characteristics:

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1. Exceptional hardness
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With a rating of 9/10 on the Mohs scale, the ruby ​​is among the three hardest minerals on the planet. Only diamond or moissanite—the two stones ranking higher on the scale—can scratch a ruby.

This characteristic ensures that ruby-set jewelry is highly durable over time. It is therefore particularly well-suited for everyday wear, such as in an engagement ring.
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2. Corundum is extremely heat-resistant
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The ruby ​​is highly resistant to high temperatures. There is no risk of damaging a ruby ​​piece through prolonged sun exposure or, for instance, when taking a dish out of the oven!
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Note: Contrary to popular belief, this trait is not shared by all gemstones—emeralds, for example, are relatively sensitive to such temperature fluctuations.
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3. One of the most iconic colors in jewelry
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One reason corundum is so highly prized is its wide range of colors: pink, orange, purple, black, blue (sapphire), and even colorless!

The ruby ​​possesses a rather rare characteristic in the gemstone world: it comes in only one color—red.
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This color is caused by the presence of chromium oxide (at a concentration of 2%). Rubies from the same deposit can exhibit different colors, although color is often linked to the stone's origin.

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RUBY QUALITY
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1. The highest grade for a colored stone is AAA quality.
 

Unlike diamonds, colored stones lack standardized, internationally recognized systems for comparison.
 

That said, the certification process for a colored stone—such as a ruby—is just as rigorous as for a diamond and involves three quality levels:

• A: denotes average, common quality.

• AA: denotes a rarer quality, typically used by small local lapidaries rather than major retailers. It represents superior quality with few flaws and rich, vibrant colors.

• AAA: the highest possible quality for colored stones. It signifies a complete absence of flaws, superior brilliance, and rich, uniform color.

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How is ruby ​​quality assessed?
 

It draws directly from the universal "4Cs" used for diamond certification!
Namely:

• Color: whether natural or enhanced by treatment,

• Weight: the stone's carat weight,

• Cut (or faceting): an assessment of the stone's faceting quality and shape,

• Clarity: the presence or absence of inclusions visible to the naked eye or under 10x magnification.

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2. Inclusions
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Natural rubies are stones that contain inclusions.
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What does this mean?
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An inclusion is a foreign element that became trapped inside the stone during its formation.
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As with most natural stones, inclusions are a perfectly normal phenomenon. In fact, it is virtually impossible to find a ruby ​​completely free of inclusions. Like a fingerprint, this phenomenon makes a stone completely unique. It is even referred to as the stone's "life." It is worth noting that chromium oxide—which gives the ruby ​​its magnificent red hue—has the chemical property of creating inclusions. Thus, chromium is responsible for both the ruby's color and its impurities. Consequently, finding perfectly clear rubies is exceptionally rare; some might even call it a natural anomaly!

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So, what do ruby ​​inclusions look like?

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They are often characteristic of the stone's origin. For instance, Burmese rubies often feature a "frost" or "white veil" within the stone—a trait not found in Mozambican rubies, which tend to be clearer and purer.

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These inclusions are traces of the stone's geological formation in a specific region—acting, in this case, as a signature of two different continents.

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FREQUENTLY ASKED QUESTIONS

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Are rubies treated?

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The vast majority of natural colored gemstones worldwide undergo heat treatment.

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What does this mean?
 

Heating a stone is a process that has been used since time immemorial on colored gemstones to preserve or enhance their color, or simply to make them more durable. It is a process that does not harm the stone; on the contrary, it actually benefits it! So, there is no need to worry about it.
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Contrary to popular belief, unheated stones are extremely rare; unless explicitly stated or backed by a specific certificate, it is highly unlikely that a stone is unheated. Be wary if you are told a ruby ​​is "unheated" without having a certificate from an independent laboratory. An unheated stone with rich color intensity is so rare that its price can be up to 100 times higher, and such stones are reserved for unique pieces in high-end jewelry.
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While this process is not classified as a "treatment" in the strict sense, it should certainly not be confused with chemical treatments—such as irradiation, fracture filling, impregnation, and dyeing—which alter the stone's natural state and are subject to government regulation.